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--[[
Host address resolver for Alpine Wall
Copyright (C) 2012 Kaarle Ritvanen
See LICENSE file for license details
]]--
module(..., package.seeall)
local familypatterns = {inet='%d[%.%d/]+',
inet6='[:%x/]+',
domain='[%a-][%.%w-]*'}
local function getfamily(addr, context)
for k, v in pairs(familypatterns) do
if string.match(addr, '^'..v..'$') then return k end
end
context:error('Malformed host specification: '..addr)
end
local dnscache = {}
function resolve(host, context)
local family = getfamily(host, context)
if family == 'domain' then
if not dnscache[host] then
dnscache[host] = {}
for rec in io.popen('dig -t ANY '..host):lines() do
local name, rtype, addr =
string.match(rec, '^('..familypatterns.domain..')%s+%d+%s+IN%s+(A+)%s+(.+)')
if name and string.sub(name, 1, string.len(host) + 1) == host..'.' then
if rtype == 'A' then family = 'inet'
elseif rtype == 'AAAA' then family = 'inet6'
else family = nil end
if family then
assert(getfamily(addr, context) == family)
table.insert(dnscache[host], {family, addr})
end
end
end
if not dnscache[host][1] then
context:error('Invalid host name: '..host)
end
table.sort(dnscache[host], function(a, b) return a[2] < b[2] end)
end
return dnscache[host]
end
return {{family, host}}
end
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